Active involvement in scientific research of persons living with dementia and long-term care users: a systematic review of existing methods with a specific focus on good practices, facilitators and barriers of involvement

Background Active involvement of persons living with dementia (PLWD) and long-term care (LTC) users in research is essential but less developed compared to other patient groups. However, their involvement in research is not only important but also feasible. This study aims to provide an overview of methods, facilitators, and barriers for involving PLWD and LTC users in scientific research. Methods A systematic literature search across 12 databases in December 2020 identified studies involving PLWD, LTC users, or their carers beyond research subjects and describing methods or models for involvement. Qualitative descriptions of involvement methods underwent a risk of bias assessment using the Critical Appraisal Skills Programme (CASP) Qualitative Checklist 2018. A data collection sheet in Microsoft Excel and thematic analysis were used to synthesize the results. Results The eighteen included studies delineated five core involvement methods spanning all research phases: advisory groups, formal and informal research team meetings, action groups, workshops, and co-conducting interviews. Additionally, two co-research models with PLWD and carers were found, while only two studies detailed LTC user involvement methods. Four distinct involvement roles were identified: consulting and advisory roles, co-analysts, co-researchers, and partners. The review also addressed barriers, facilitators, and good practices in the preparation, execution, and translation phases of research, emphasizing the importance of diversity, bias reduction, and resource allocation. Trust-building, clear roles, ongoing training, and inclusive support were highlighted. Conclusions Planning enough time for active involvement is important to ensure that researchers have time to build a trusting relationship and meet personal needs and preferences of PLWD, LTC users and carers. Researchers are advised not to presume the meaning of burden and to avoid a deficit perspective. A flexible or emergent design could aid involved persons’ ownership of the research process. Trial registration Prospero 2021: CRD42021253736. Supplementary Information The online version contains supplementary material available at 10.1186/s12877-024-04877-7.


Background
In research characterized by active involvement, the target group plays a pivotal role in shaping research decisions and outcomes, directly impacting them.Involving patients in health research offers significant benefits [1,2]: it enhances participant recruitment [2], refines research questions [2], aligns study results with the target population [1,2], and promotes effective implementation of findings [1].Active involvement of patients has also benefits for themselves, namely an enhanced understanding of research, building relationships, personal development, improved health and wellbeing, and enjoyment and satisfaction [3,4].It gives them a sense of purpose and satisfaction through their tangible impact.
However, for long-term care (LTC) users and persons living with dementia (PLWD) active involvement in research is less developed than for other patient groups [5,6].PLWD and LTC users share similar care needs, encompassing assistance with activities of daily living (ADLs), medication management, medical condition monitoring, and emotional support.Furthermore, a substantial portion of LTC users comprises individuals living with dementia [7].Additionally, statistical data from the United States reveals that one in four older individuals is likely to reside in long-term care (LTC) facilities [8], and approximately forty to eighty percent of LTC residents in the United States, Japan, Australia, and England experience dementia or severe memory problems [7,9].
Due to these considerations, we have chosen to combine the target audiences of PLWD and LTC users in our systematic review.However, it's important to note that while there are potential advantages to combining these target groups, there may also be challenges.PLWD and LTC users may have varying needs, preferences, and experiences, including differences in care requirements driven by individual factors like the stage of dementia, coexisting conditions, and personal preferences.Therefore, it's imperative to conduct comprehensive research and involve these communities to ensure that involvement approaches are not only inclusive but also tailored to meet their specific requirements.
Given our ageing population and the intricate health challenges faced by PLWD and LTC users, including their vulnerability and shorter life expectancy in old age, it's crucial to establish effective research involvement methods.These individuals have unique needs and preferences that require attention.They possess a voice, and as researchers, it is our responsibility to not only listen to them but also actively involve them in the research process.Consequently, it is essential to identify means through which the voices of PLWD and LTC users can be effectively heard and ensure that their input is incorporated into research.
Fortunately, publication of studies on involvement of PLWD and LTC users in scientific research is slowly increasing [5,[9][10][11].A few reviews have described how PLWD and LTC users were involved [5,9,10].However, with the increasing attention for involvement, the understanding of when involvement is meaningful grows and stricter requirements can be imposed to increase the quality of active involvement [12,13].To our knowledge there is no up to date overview of involvement methods used with either or both PLWD and LTC users.Such an overview of involvement methods for PWLD and LTC users would provide a valuable, comprehensive resource encompassing various stages of the research cycle and different aspects of involvement.It would equip researchers with the necessary guidance to navigate the complexities of involving PLWD and LTC users in their research projects.
Recognizing the need to enhance the involvement of PLWD and LTC users in scientific research, this systematic review aims to construct a comprehensive overview of the multiple methodologies employed in previous studies, along with an examination of the facilitators and barriers of involvement.Our overarching goal is to promote inclusive and effective involvement practices within the research community.To achieve this objective, this review will address the following questions: (1) What kind of methods are used and how are these methods implemented to facilitate involvement of PLWD and LTC users in scientific research?(2) What are the facilitators and barriers encountered in previous research projects involving PLWD and LTC users?

Information sources, search strategy, and eligibility criteria
In preparation of the systematic literature search, key articles and reviews about involvement of PLWD and LTC users in research were screened to identify search terms.In addition, Thesaurus and MeSH terms were used to broaden the search.The search was conducted on December 10, 2020, across multiple databases: PubMed, Medline, Embase, Emcare, Web of Science, Cochrane Library, PsycINFO, Academic Search Premier, JSTOR, Social Services Abstracts, Sociological Abstracts, Psychology and Behavioral Sciences Collection.The search terms were entered in "phrases".The search strategy included synonymous and related terms for dementia, LTC user, involvement, research, method, and long-term care.The full search strategy is provided in supplement 1.
After conducting the search, records underwent initial screening based on titles and abstracts.Selected reports were retrieved for full-text assessment, and studies were evaluated for eligibility based on several criteria.However, no restriction was made regarding publication date.First, to be included studies had to be written in English, German, French, or Dutch.Second, we only included original research studies.Third, studies were excluded when the target group or their representatives were not involved in research, but only participated as research subjects.Fourth, studies were excluded when not describing involvement in research.Therefore, studies concerning involvement in care, policy, or self-help groups were excluded.Fifth, the focus of this systematic review is on methods.Therefore, studies with a main focus on the results, evaluation, ethical issues, and impact of involvement in research were excluded.Additionally, we have not set specific inclusion or exclusion criteria based on study design since our primary focus is on involvement methodologies, regardless of the chosen research design.Sixth, the included studies had to concern the involvement in research of PLWD or adult LTC users, whether living in the community or in institutional settings, as well as informal caregivers or other representatives of these groups who may represent PLWD and LTC users facing limitations.Studies that involved LTC users that were children or 'young adults' , or their representatives, were excluded.Studies were also excluded if they involved mental healthcare users if it remained unclear if the care that they received entailed more than only treatment from mental healthcare providers, but for example also assistance with ADL.

Terminology
For readability purposes, we use the abbreviation PLWD to refer to persons diagnosed with dementia, and we use the abbreviation LTC users to refer to persons receiving long-term care, at home or as residents living in nursing homes or other residential facilities.We use the term carers to refer to informal caregivers and other representatives of either PLWD or LTC users.As clear and consistent definitions regarding participatory research remains elusive [14,15], we formulated a broad working definition of involvement in research so as not to exclude any approach to participatory research.We defined involvement in research as "research carried out 'with' or 'by' the target group" [16], where the target group or their representatives take part in the governance or conduct of research and have some degree of ownership of the research [12].It concerns involvement in research in which lived experienced experts work alongside research teams.We use the terms participation and participants, to refer to people being part of the research as study subjects.

Selection process, data-collection process, and data items
Titles and abstracts were independently screened by the first and second author (JG and LT).Only the studies that both reviewers agreed and met the inclusion criteria were included in the full-text screening process.Any uncertainty about whether the studies truly described a model or approach for involvement, was resolved by a quick screening of the full-text paper.The full-text screening process was then conducted according to the same procedure by JG and LT.Any disagreement was resolved by discussion until consensus was reached.If no agreement could be reached, a third researcher (MC) was consulted.References of the included studies were screened for any missing papers.
The following information was collected on a data collection sheet in Microsoft Excel: year and country of publication, topic, research aim, study design, living situation of involved persons (at home or institutionalized), description of involved persons, study participants (study subjects), theories and methods used, type/role(s) of involvement, research phase(s), recruitment, consent approach, study setting, structure of participatory activities, training, resources, facilitators, barriers, ethics, benefits, impact, and definition of involvement used.
JG independently extracted data from all included studies, the involved co-researcher (THL) independently extracted data from two studies, the second author (LT) from five.Differences in the analysis were discussed with the co-researcher (THL) and second author (LT) until consensus was reached.As only minor differences emerged, limited to the facilitator and barrier categories, data from the remaining studies was extracted by JG.

Risk of bias assessment
Every research article identified through the systematic review exclusively comprised qualitative descriptions of the involvement method(s) employed.Consequently, all articles underwent evaluation using the Critical Appraisal Skills Programme (CASP) Qualitative Checklist 2018 [17], as opposed to the checklists intended for quantitative or mixed methods research.All included studies were independently assessed on quality by two reviewers (JG,LT) and any disagreement was resolved by discussion until consensus was reached.The CASP Qualitative Checklist consists of ten questions.The checklist does not provide suggestions on scoring, the first author designed a scoring system: zero points if no description was provided ('no'), one point if a minimal description was provided ('can't tell') and two points when the question was answered sufficiently ('yes').The second question of the checklist, "is a qualitative methodology appropriate", was not applicable to the aims (i.e., to describe involvement) of the included studies and was therefore excluded.The tenth question was translated into a 'yes' , 'can't tell' , or 'no' score to fit the scoring system.A maximum of eighteen points could be assigned.

Synthesis methods
Tables were used to summarize the findings and to acquire an overview of (1) the kinds of methods used to enable involvement of PLWD, LTC users, or carers in scientific research, and (2) the facilitators and barriers for involving this target group in scientific research.As to the first research aim, the headings of the first two tables are based on the Guidance for Reporting Involvement of Patients and the Public, long form version 2 (GRIPP2-LF) [18].Because our systematic review focusses on methods, only the topics belonging to sections two, three, and four were included.Following Shippee et al., three main research phases were distinguished: preparation, execution, and translation [19].Furthermore, the following fields were added to the GRIPP2-LF: First author, year of publication, country of study, setting of involvement, frequency of meetings, and a summary description of activities.
Concerning the second research aim, the extracted facilitators, barriers, and good practices were imported per study in ATLAS.ti for qualitative data analysis.Following the method for thematic synthesis of qualitative studies in systematic reviews [20], all imported barriers, facilitators and good practices were inductively coded staying 'close' to the results of the original studies, which resulted in 50 initial codes.After multiple rounds of pile sorting [21], based on similarities and differences and discussions in the research team, this long code list was grouped into a total of 27 categories, which were thereafter subsequently organized into 14 descriptive themes within the three research phases (preparation, execution, translation).

Study selection and characteristics
The Prisma Flow Diagram was used to summarize the study selection process [22].In the full text screening, 72 of the 93 remaining studies were excluded because they were not original research articles (n = 5), not about involvement (n = 8), not about involvement in a research project (n = 1), they did not describe a model or method for involvement (n = 34), or they were not about PLWD or LTC users (n = 24).The search resulted in 18 publications eligible for analysis (Fig. 1).

Phases and methods of involvement
Table 2 describes the involvement methods used for and the implementation of involvement in research.The included studies jointly presented methods for involvement in the three main research phases [19].Regarding the preparation phase, which involves the preparatory work for the study, only three studies provided detailed descriptions of the methods employed [26,30,32].The execution phase, encompassing the actual conduct of the research, was most frequently discussed [23][24][25][26][27][28][29].Five studies addressed the translation phase [13,25,31,36,37], where the focus shifts to translating research findings into actionable outcomes.
The eighteen studies introduced a variety of involvement methods, categorizable into five groups: 1) advisory groups, 2) research team meetings (both formal and informal), 3) action groups, 4) workshops, and            -First workshop: a summary of the systematic review and a list of models were provided two weeks prior to the meeting.In the meeting the group developed a framework -Second workshop: discussion on selection of summaries of interviews and mapping of models against developed framework -The results were collated by the research team and a draft report was sent to all involved persons for feedback   The co-researchers conducted the interview with some help from the academic researcher.The academic researcher met with co-researchers in their homes to remind them about the purpose and process of the interviews and travelled together by car to the interview participants 3. Immediately after the interview, the academic and co-researcher shared thoughts on the process and content of the interview 4.After each round of interviews a meeting was organized in which academic and co-researchers discussed key themes and issues a Involvement in more research phases, but these were not elaborated on 5) co-research in interviews.In five studies, individuals including PLWD, LTCF residents, carers, and health professionals participated in advisory/reference groups [25][26][27]32], working groups [27], and panels [28].These groups offered valuable feedback on research aspects, spanning protocols, design, questionnaires, and implementation of research.Meetings occurred at varying frequencies -monthly, quarterly, or biannually.Two studies exemplify diverse research collaboration settings.One involving older individuals within an academic research team of five [37], and another featuring a doctoral student and a co-researcher conducting informal monthly discussions at a local coffee shop [31].Brown et al. sought to minimize power differentials and enhance inclusivity [37], while Mann and Hung focused on benefiting people with dementia and challenging negative discourse on dementia [31].
An additional five studies employed methods involving frequent meetings, including action [35,39], inquiry [23], and discussion groups [29,36] In these groups, involved persons with lived experience contributed to developing a shared vision and community improvements, such as enhancing the mealtime experience in care facilities [35].
Seven studies involved individuals through workshops, often conducted over one or two sessions.These workshops contributed to generating recommendations [37], informing future e-health designs [29,30], and ensuring diverse perspectives and lived experiences were included in data analysis [13,24,32,33].In three studies, representatives worked as co-researchers in interviews, drawing on personal experiences to enhance the interview process, making it more dementia-appropriate and enriching data collection [13,32,34].Finally, one study involved representatives in the recruitment and conduct of interviews [38].

People involved
The number of persons involved varied from a single co-researcher [31] to 34 panel individuals providing feedback on their experiences in a clinical trial [28].Thirteen studies focussed on PLWD: eleven involved PLWD themselves [23][24][25][26][27][29][30][31][32][33][34], one exclusively focused on caregivers [13], and another one involved people without or with mild cognitive impairment, who participated in a study examining the risks of developing Alzheimer's disease [28].Although not all articles provided descriptions of the dementia stage, available information indicated that individuals involved typically fell within the early to mid-stages of dementia [29,30,[32][33][34].Next to PLWD and carers, two studies additionally involved organizational or advocacy representatives [25,27].The other five studies concerned older adults living in a LTC facility.Two of them involved older residents themselves [35,39], the other three carers, older community/client representatives or health care practitioners [36][37][38].

Roles and level of involvement
Four general roles could be identified.First, consultation and advisory roles were held by PLWD and carers [25][26][27][28][29][30]32], where involved persons share knowledge and experiences to make suggestions [32], but the research team retained formal decision-making power [25].Second, PLWD were involved as co-analysts in data analysis [24,32,33].Co-analysts influence data analysis, but the decision-making power remained with academic researchers [24].Third, in six studies the co-researcher role was part of the research design in which involved persons and researchers steer and conduct research together [13,23,31,32,34,36].Finally, two studies partnered with LTC residents [35,39], with residents at the core of the group, and positioned as experts by experience [39].Residents had the decision-making authority regarding how to improve life in LTC facilities [35].

Models for involvement in research
Only two studies designed a model for co-research with PLWD [23] or their carers [13] across all research phases.These models underscored the importance of iterative training for co-researchers [13,23] and academic researchers [23].Furthermore, these studies advocate involving co-researchers early on in the research process [13] and in steering committees [23].Co-researchers can be involved in designing research materials [23], conducting interviews [13,23], analysing data [13], and codisseminating findings [13,23].Additionally, one study stressed involving PLWD in identifying (future) research priorities [23].

Preparation phase
Table 3 describes the barriers, facilitators, and good practices per main research phase.Lack of diversity in ethnicity and stages of dementia in the recruitment of involved persons is mentioned as a recurring barrier [26,28,32,33].The exclusion of people with cognitive impairments is partly due to gatekeepers' and recruiters' bias towards cognitively healthy people [28,32].It is stressed that researchers should refrain from making assumptions about the abilities of PLWD and ask the person what he/ she is willing to do [31].It is considered good practice to involve people regardless of cognitive abilities [23], based on skills, various personal characteristics [13] and, if possible, relevant prior experience [38].
Many studies stress the importance of building a mutual trusting relationship between involved persons and academic researchers [13,23,31,33,34,37].A good

Preparation
Recruitment Recruit involved persons, regardless of cognitive abilities [23], based on skills, different personal characteristics [13] and prior relevant experience [38] Recruiting through gatekeepers (health professionals and carers) can result in the exclusion of less articulate or critical people [35], people with cognitive impairments [28], and people living with dementia [32].A lack of identification with medical labels might lead to difficulties in recruitment [30].Involvement of people with mild to moderate dementia does not imply representation of the experiences of people with more advanced dementia [33,34], and involving carers might put carer' experiences in the forefront [13,32].Lack of diversity, such as differences in ethnicity and religion, is an issue in PPI [26,33].Snowballing can result in less diversity [13].Assuming "peerness" between co-researcher and interviewee based on sharing a dementia diagnosis and both being older persons is not enough [34].Co-research might favour people who embrace a dementia identity and silence those who have a more self-maintaining stance [34].The voluntary nature of PPI might imply that the skills requirements for performance of the involvement role(s) are not met [13] Work alongside healthcare professionals and services to recruit people who are hard to reach [30].
Recruiting through existing networks and peer support groups is a good basis for building relationships [24,38].Involving representatives with different personalities and skills provides multiple unique perspectives and enhances data collection [13] Role description Explore and discuss the purpose, scope, and expectations of involvement [26,28] at the beginning and throughout the project [29].Provide a common, but adaptable framework [28].Offer personal and professional development opportunities [13,32] to make involved persons' roles more rewarding, and support involved persons holding multiple roles [32].Co-design the role in collaboration with involved persons, taking into account skills, preferences, and goals [13], for example using a forward planning activity sheet to enable involved persons to indicate their interests [32] Naturally evolving roles result in a lack of clarity about expectations and involvement in irrelevant topics and tasks [37].Integrating an involvement role in predefined governance structures was difficult and panels have not always moved in line with initial researcher expectations [28].Access to ICT when being a co-applicant, complex language and procedures used to structure involvement roles can potentially exclude experiences of persons living with dementia [32] The identification of clear roles, activities and tasks, and expressing expectations and values ensures that involved persons feel part of the team [38], prevents 'tokenistic' involvement [28] and can help the involvement process [32].It is important to understand the involved persons' motivation for involvement to ensure personal needs are met [32] Table 3 (continued)

Relationships and group dynamics
Involved persons: Take time to build a mutual trusting relationship [13,23,34], to foster freedom of expression [33] and break down social barriers [37].Become familiar with the strengths, limitations and what the person is comfortable with in order to maximize contribution [31,34].Reflect on group dynamics through a hermeneutic-dialectical process [35] Long-term care facility (LTCF) staff: Developing a trusting relationship with LTCF staff, particularly with management and administrators, is important for involvement research in these settings to succeed [35,36,39] Involved persons: Researchers need to stop making assumptions about the abilities of persons living with dementia [31] LTCF staff: LTCFs are highly hierarchical environments [35,39].Distrust of management and other staff towards involvement research process can lead to drop-out of organisation [36] and low staff participation [39] Involved persons: Allow time for socialising [29], organize social meetings/activities [37,38] and meetings in the home of lay researchers [13].
Pay attention to difference in roles and responsibilities [38].Meet regularly/monthly [13,38] even when there are no research meetings to keep involved persons motivated [34].Travel together to interviews to brief and debrief [13,34].Avoid being tokenistic [13] and see the person through an appreciative lens [31].To develop a shared voice it is important, particularly for marginalized groups, to meet in a homogenous group [35] and in small groups for involved persons s to get to know each other and feel confident to express their views [29] LTCF staff: Developing a shared vision is a condition for quality and validity [36].A trusting relationship with board members and management can facilitate support of other staff [35,36], inhibit reluctance to involvement, and prevent scheduling conflicts [39].Develop strategies to motivate LTCF staff to become involved [39] Training of academic and non-academic involved persons Provide iterative coaching and training sessions [23,31], based on emerging needs [13] or when lay researchers indicate an interest [37], to challenge the dominant view of scientific knowledge, increase reflexivity [36], ensure an appropriate skill set, establish understanding of the involvement process [28], and provide guidance and tactics to fulfil co-research role [32,33].Training on everyday ethics [31], how to build an equal relationship, reducing technical language and recruitment [28] should be offered to academic researchers [13,23] Training raises costs [28], is at odds with the principle of valuing experiential knowledge [37] and should not aim to make co-researchers into 'expert' researchers [32] Training fosters confidence, skills, building rapport, a positive experience and will empower involved persons to engage, motivated, meaningfully and equally in the research process [13,33,38] Financial compensation Provide financial compensation [13,32] for travel expenses, shopping [26], attendance at meetings [25,27] and provide print-outs to avoid printing costs [26] Project funding for involvement compensation was underbudgeted, involved persons only received compensations for travel expenses and accommodation [27].Resourcing of travel expenses of involved persons was an issue [28].Assistance with transportation should have been provided [25] Compensation serves to acknowledge the invaluable contribution of involved persons to the research [13] Table 3 (continued)

Facilitators
Practicalities: Time, budget and setting Plan and budget for additional administration, time, staff, and involvement activities early on [13,28,33,37].Plan extra time for involvement activities [13,29,34].The setting and timing of involvement activities matter; pay attention to: social status of location, availability of disabled access, close to facilities, and ensure that the place is familiar, comfortable, and easily accessible (close to public transport and car parking) [29][30][31]34] Limited resources restrict the desire of involved persons to meet more often [28] and hinder sustainability of initiatives [39].Due to time constraints, representatives only supported 20% of the interviews [38].Some forms of involvement such as co-research and action research are more resource (competences, time, and commitment of researcher) and budget intensive than other forms of involvement and may delay the research process [13,32,36,39].The physical space of involvement activities should be considered more [33], meeting in an unfamiliar place (e.g., office) could lead to stress and more distractions (e.g., less concentration) [31] Virtual meetings are accessible regardless of location and less time consuming [26].Empower involved persons to ensure meetings are led by them and use staff in support roles [28].Availability of financial resources is important to implement developed ideas [35].Develop strategies to sustain initiatives (e.g., resident councils could facilitate resident groups) [39].
Meeting in a familiar environment allows for robust involvement and enhanced concentration for people living with dementia [31] Execution Planning of involvement design Plan long-term collaboration with lay researchers early in the research [13].Ensure ethics approval is in place [13] and when research ethics committees see co-analysts as research subjects, make certain no new data is gathered [24].Make agreements on the confidential nature of research discussions and materials [25] and on what information is shared during coresearch interviews [13,32].Ensure representation on research governance level [27], in steering and advisory groups [23].Involving persons living with dementia as co-researchers can open up an empathic level of knowledge [23].Invite co-researchers to analyse data independently, rather than verify the interpretations [33] Need of an ethical framework for co-researchers which formalizes expectations, responsibilities, and confidentiality [23].When interview guides are ethically approved prior to co-researcher involvement, this will limit the capacity of co-researchers to direct the interview [32].
The empathic bond between co-researcher and interviewee can have disadvantages, such as entrusting information in private [13],wanting to help the interviewee [32] and shared experiences might influence interviewee responses [23].The involved persons-led design created the potential for conflicting ambitions of involved persons and researchers [28] Early involvement increases confidence [13,31], enables full involvement and time to build a trusting relationship [31].Involve co-researchers in future work (e.g., identifying research priorities) in order to reposition people living with dementia at centre stage [23].An emergent design facilitates co-ownership and ensures the research is responsive to the involved person's experiences [35].In relation to multisite involvement activities with central terms of reference, allow local adaptions to nurture ownership of the local group [28] Table 3 (continued)

Facilitators
Academic culture and experiential knowledge Lived experiences of people living with dementia should be central and guide development of research [23,27].Researchers should have an open mind, give up control, be open to having their traditional academic views challenged, not be dismissive of lay people's views, step out of their comfort zone [13], value experiential knowledge and not make assumptions based on a deficit perspective [31].Use a consensusbased approach [25] and maintain balance in joint decision making [23] Use of academic jargon [13,37], rapid pace of discussions [37], (subtle) power relations [36,37], and difference between 'academic time' and 'dementia time' [24] can inhibit involved persons from expressing their views [13] and to tell about their world, and can make involved persons inclined to give socially desirable answers [37].The dominance of the biomedical model in research decision making, the conventional social science research paradigm, the authority of research and adherence to 'rigorous' academic models can lead to undermining the contributions of lay researchers [13] and are a challenge to the impact of involvement, especially in relation to dementia studies where people are historically silenced [24,32].Including lay people in research meetings allows less space for academic talk (less efficient), expressing personal comments was not always appreciated [37] and lived experiences of lay researchers can clash with academic views and priorities [13,23], which can be uncomfortobale for both lay researchers and academic researchers [32].Some people might feel intimidated by the titles of academics [31] and having confidence to share personal experiences [13] or indicating a lack of understanding can be challenging [37] Separating technical topics from general meetings [37], making a glossary of common terms to understand each other's jargon [37], slow down to examine assumptions about dementia, reflect on the relationship and how power is shared [31], and a relational empowerment approach to facilitation, in which the facilitator acknowledges the other's power and disempowerment, and adapts to fluctuations, could minimize power differentials [35] Table 3 (continued)

Facilitation of involvement
Facilitation is very important [28,35] and is a skill that needs practice [23].Facilitation should include: managing and guiding involvement processes, ensuring equality of power, safeguarding the autonomy of involved persons [32], a non-directive approach, good listening skills, reflecting the words of involved persons, acceptance, positive regards for opinions [33], minimize control, embracing evolving process, appropriate risk assessments, offer professional support, be creative [23], allow time for repetition of information and clarification of tasks [29].
Inform involved persons how their input has shaped, guided, and made a difference in the research [31] at the beginning of meetings [26] and throughout the study [30] Need for more time, opportunities for clarification [37] and more support of academic and lay researchers to ensure meaningful and effective involvement [13].It takes time and effort to explain that scientific knowledge is not a pre-set prescription for change and needs to be contextualized, which requires reciprocal adequacy [36] Involved persons have to be encouraged and reminded by facilitators that they are not research subjects [32,33], are experts of lived experience [39], their knowledge and actions are valid and essential [36], that they can challenge research documents, and to note down thoughts [37].This implies that facilitators reflect on their own actions and those of others involved [36].Maintain a structured (i.e., set agenda), but informal and flexible meeting style, and ensure an efficient operation to encourage involved persons to express their views and enable their voices to be heard [27,28].Showing the impact of involvement is important to motivate involved persons s and to increase energy [31].
It facilitates a feeling of being taken seriously [28] and of intrinsic reward [32].Active contribution of principal investigator was experienced as empowering [28] Burden and support Offer physical, emotional [13], and peer support [23] in relation to personal ageing and mortality [38].Take into consideration potentially changing needs and deterioration in capabilities when involving persons living with dementia [30,33] and help involved persons to find support when needed [29].Identify individuals in the research team or an independent individual as a focal point of contact [28] whom involved persons can approach if they have concerns [37].Involve experienced staff who have practical experience of working with persons living with dementia and their families [29], to offer guidance and support [30] Some carers have dropped out due to caring difficulties [26].Hearing or observing disturbing situations which sometimes resonate with involved persons' own experiences can be distressing [13,32,38].Involving only one person living with dementia in a group of people is experienced as intimidating and researchers showing compassion as disturbing [32].
Maximising contribution of co-researcher without overburdening him or her is a challenge [31] Avoid too fast a pace for people who may tire easily [24,29,30] plan regular breaks in meetings [24,25], be flexible regarding time frames for specific tasks and allow a 'time-out' when necessary [29].Briefing and debriefing after co-researcher interviews [32] is important to provide emotional support [13].Involve a larger team of persons to reduce the sense of burden and responsibility [37].Involve carers or family members of persons living with dementia in the process to ensure support [25,29,30] and provide tailored support to avoid overburdening the carer [29].Peer support is of importance to ensure wellbeing in the process [23], and meeting the same people at each session is beneficial for persons living with dementia and their carers [26].
Do not assume what the meaning of burden is or what support is needed [30,31], treat people as individuals and ask the person living with dementia what he/she is willing to do or if support is needed [30,31] Table 3 (continued)

Facilitators
Communication/information Establish ground rules for communication [37] and follow guidance on communicating with persons living with dementia [33].Record and take minutes of meetings to share meeting notes with the broader research team [25] and all involved persons [26].Share all research outputs through email or handouts [26] Too much and irrelevant or inadequate information was shared [37], this is a problem specifically when taking into account differing abilities of involved persons [23].Video calling-related technical problems made communication difficult [37] To avoid an overload of information, make individual agreements on the type, amount, and format of information sent to involved persons [27,37].Provide summaries of key points and clearly state why the information is sent [37] Inclusive tools Provide pens, paper during meetings, accessible meeting materials in advance [25] and folders to organize information [37] Use of creative visual tools should have been considered more [33] To enable involvement of persons living with dementia use visual tools [30], such as picture word cards, storyboards and cue cards, to prompt memories [24,34].Modify methods and develop interactive activities to enable involvement [30,31].To increase visual distinctiveness, provide documents in large font [26], on coloured paper [24], with graphics and space for involved persons' comments [25].Provide audio-recorded notes when involved persons have difficulties with reading [26] Translation

Findings and dissemination
Findings should be meaningful to, accessible to, serve the interest of, and benefit people living with dementia [23,31].Use GRIPP guidelines to report on different ways of knowing and who decides [32] Use social media and creative/visual methods to communicate research findings with the aim of increasing accessibility and extend the discourse on representation of persons living with dementia [23] Reflection and evaluation Determine how success of involvement will be monitored [28].Evaluate and reflect on impact [26], effectiveness [23] and benefits of involvement [33] and on process of collaboration [31] through: writing down experiences in reflective diaries [13], using a template or paper format to guide reflection and evaluation [38] with open-ended questions [33], and joint reflection after each session and at the end of the programme [26] There is a need for pre-set robust evaluation measures to assess impact and success of involvement [28,33] Reflection and evaluation can improve subsequent sessions [26], foster self-reflection and introspective learning [23], promote personal and professional development [13], and can help to address dementia-related assumptions [31] relationship is believed to break down social barriers [37], foster freedom of expression [33], and thereby avoiding tokenistic involvement [13].In addition, spending time with these persons is important to become familiar with an individual's strengths and limitations [31].Opting for naturally evolving involvement roles was mentioned as a barrier, as this may result in conflicting expectations and irrelevant tasks [37].A clear role description and clarification of tasks is key to balancing potentially different expectations of the involved persons and researchers [26,28,29,32,38].When designing a role for involvement in research, good practices dictate taking into account personal skills, preferences, development goals, and motivation for involvement [13,32].This role should ideally be designed in collaboration with involved persons [13,32].
The perception of providing training to involved persons is ambivalent.Studies cited that training should not aim to transform them into "pseudo-scientist" [32,37] and that it raises the costs for involvement [28].However, multiple scholars emphasize the importance of providing iterative training to facilitate meaningful involvement and development opportunities [13, 23, 28, 31-33, 36, 37].Training can empower involved persons to engage in the research process equally and with confidence, with the skills to fulfil their role [13,33,38].However, the implementation of training may present a potential conflict with the fundamental principle of valuing experiential knowledge [37] and should avoid the objective of transforming co-researchers into 'expert' researchers [32].Academic researchers should also be offered training on how to facilitate meaningful involvement [13,23,28,31].
Limited time and resources were mentioned as barriers to involvement that can delay the research process [13,33,36,39], restrict the involvement [28] and hinder the implementation of developed ideas [39].Financial compensation for involvement is encouraged [25][26][27]32], as it acknowledges the contribution of involved persons [13].Thus, meaningful involvement in research requires adequate funding and infrastructure to support the involvement activities [13,28,33,37].

Execution phase
The use of academic jargon and rapid paced discussions [13,37], power differentials, and the dominant discourse in biomedical research on what is considered "good science" can limit the impact of involvement [13,24,32,36,37].Facilitating researchers should reflect on power differentials [35] and how decision-making power is shared [31].Other facilitating factors are making a glossary of terms used and planning separate meetings for "technical topics" [37].In addition, an emergent research design [35] or a design with flexible elements [28] can increase ownership in the research project and provide space for involvement to inform the research agenda [28,35].This requires academic researchers to value experiential knowledge and to have an open mind towards the evolving research process [13,23,31].
Furthermore, managing the involvement process and ensuring equity in the collaboration [13,32,33], facilitating researchers must encourage involved persons to voice their perspectives.This means that they sometimes need to be convinced that they are experts of lived experience [32,33,36,37,39].To enable involvement of PLWD, the use of visual and creative tools to prompt memories can be considered [24,30,33,34], as well as flexibility in relation to time frames and planning regular breaks to avoid too fast a pace for people who may tire easily [24,25,29,30].
Involvement can be experienced as stressful [13,32,38] and caring responsibilities may interfere [26].Tailored [29] physical and emotional support should therefore be offered [13,23,38] without making assumptions about the meaning of burden [30,31].Moreover, being the only PLWD involved in an advisory group was experienced as intimidating [25] and, ideally, a larger team of PLWD is involved to mitigate responsibilities [37].PLWD having a focal point of contact [28,37] and involving nurses or other staff with experience working with PLWD and their carers [29,30] are mentioned as being beneficial.Some stress the importance of involving carers when engaging with PLWD in research [25,29,30].
To avoid an overload of information that is shared with the involved persons, tailoring information-sharing formats to individual preferences and abilities is essential to make communication effective [27,37].

Translation
Two studies indicated a need for more robust evaluation measures to assess the effect of involvement [28,33].Reflection and evaluation of the involvement serves to improve the collaboration and to foster introspective learning [13,23,26,31].The included studies evaluated involvement through the use of reflective diaries [13] or a template [38] with open-ended questions [33].
Two studies postulate that findings should benefit and be accessible to PLWD [23,31].The use of creative tools not only enables involvement of PLWD, but can also increase accessibility of research findings and expand the present representation of PLWD [23].

Discussion
The 18 included studies presented multiple methods for involvement in all three research phases.We found five types of involvement: advisory groups, (formal and informal) research team meetings, action groups, workshops, and co-conducting interviews.Only two studies described methods for involvement of LTC users in research.Involved persons were most often involved in consulting and advisory roles, but also as co-analysts, co-researchers, and partners.Involved persons' roles can evolve and change over time.Especially as involved persons grow into their role, and gain confidence and knowledge of the specific research project, a more active role with shared responsibilities can become part of the research project.In addition, multiple involvement roles can be used throughout the research depending on the research phase.
Compared to the five types of involvement that we identified, other literature reviews about involvement methods for LTC users and PLWD in research also described advisory groups [10] and workshops [5,11], and methods that were similar to research team meetings (drop-in sessions and meetings [11]).Methods for action research (action groups) and co-conducting research (interviews) were not included by these other review studies.In addition to our findings, these other reviews also described as involvement methods interviews and focus groups [5,10] surveys [10], reader consultation [11].Those types of methods were excluded from our study, because our definition of involvement is more strict; collecting opinions is not involvement per se, but sometimes only study participation.Moreover, compared to these previous reviews we set a high standard for transparency about the participation methods and the level of detail at which they are described.
Engaging the target group in research, particularly when collaborating with PLWD, LTC users, and carers, involves navigating unforeseen challenges [40].This requires academic researchers to carefully balance academic research goals and expectations, and the expectations, personal circumstances and development goals related to the involved person.The aim is to maximize involvement while being attentive to the individual's needs and avoiding a deficit perspective.Effective communication should be established, promoting respect, equality, and regular feedback between all stakeholders, including individuals living with dementia and LTCF staff.Building a mutual trusting relationship between involved persons and academic researchers through social interaction and clear communication is key to overcome barriers and ensure meaningful involvement.Inclusivity and empowerment, along with fostering an environment where diverse voices are heard, are crucial for the success of involvement in research.Our results are in line with a recent study concerning the experiences of frail older persons with involvement in research, confirming the importance of avoiding stereotypic views of ageing and frailty, building a trusting relationship, and being sensitive to older persons' preferences and needs [41].
Furthermore, our results show that training academic researchers and involved persons is essential to develop the skills to facilitate involvement and to fulfil their role with confidence, respectively.Whilst the need for training is acknowledged by others [41,42], there are legitimate objections to the idea of training involved persons, as the professionalization underpinning the concept of training is at odds with voicing a lay perspective [43,44].Furthermore, it is argued that experiential knowledge is compromised when training is structured according to the dominant professional epistemology of objectivity [45].Therefore, training of involved persons should not focus on what researchers think they ought to know, but on what they want to learn [41].
Academic culture was frequently mentioned as a barrier to meaningful involvement.This result resonates with the wider debate related to involvement in health research which is concerned about active or "authentic involvement" being replaced with the appropriation of the patient voice as an add-on to conventional research designs [12,46].It is argued that such tokenistic involvement limits the involved persons' ability to shape research outcomes [46].To reduce tokenism requires a culture shift [13].We believe that due to the strict definition of involvement and high transparency standard used in this review, tokenistic approaches were excluded.This may set an example for how to stimulate making this culture shift.
Furthermore, the importance of practical aspects such as funding and, by extension, the availability of time should not be underestimated.Adequate funding is necessary for compensation of involvement, but also to ensure that researchers have ample time to plan involvement activities and provide personalized support for PLWD, LTC residents and their carers.Funding bodies increasingly require involvement of the public to be part of research proposals.Yet, support in terms of financial compensation and time for the implementation of involvement in research is rarely part of funding grants [42].In addition, whereas an emergent design could aid the impact of involvement, funders often require a preset research proposal in which individual components are already fixed [5,47].This indicates that not only do academic researchers and culture need to change, academic systems also need to be modified in order to facilitate and nurture meaningful involvement [47].

Strengths and limitations
A key strength of this review is the inclusion of over ten scientific databases, with a reach beyond the conventional biomedical science databases often consulted in systematic reviews.Besides, we believe that we have overcome the inconsistent use of terminology of involvement in research by including also other terms used, such as participation and engagement, in our search strategy.However, there was also inconsistency in length of publications and precision of the explanation of the process of involvement.E.g., involvement in the execution phase was often elaborated on, contributions to the research proposal and co-authoring research findings were only stated and not described.This presented challenges for data extraction and analysis, as it was not always possible to identify how the target group was involved.Involvement in these research phases is therefore not fully represented in this review.
The included studies in this review, the majority of which are of high quality, provide methods for involvement of PLWD and LTC users in research and they do not explicitly attend to the effectiveness or impact of the method for involvement used.Therefore, a limitation of this review is that it cannot make any statements regarding the effectiveness of the involvement methods included.Moreover, our target population was broad, although PLWD and LTC users are largely overlapping in their care needs and share important features, this may have led to heterogeneous results.In future research, it would be interesting to interpret potential differences between involvement of PLWD, LTC users, and their carers.However, as we expected, the amount of literature included in our analyses was too limited to do so.Furthermore, whereas the broad target group is a limitation it is also a strength of our review.Limiting our search to specifically persons living in LTC facilities would have provided limited methods for involvement of persons living with dementia.Our broad target groups enabled us to learn from research projects in which people living with early staged dementia are directly involved from which we can draw lessons on the involvement of people with more advanced stages of dementia and persons living with cognitive problems who live within LTC facilities.
Since January 2021 quite some research has been published about the importance of involvement in research.Although we had quickly screened for new methods, we realise that we may have missed some involvement methods in the past years.There will be a need for a search update in the future.

Implications for future research
Our review shows that a flexible and emergent design may help to increase involved persons' influence on and ownership in the research process.However, not all research objectives may be suitable for the implementation of an emergent design.Future research should therefore examine how aspects of a flexible emergent design can be integrated in, e.g., clinical research without compromising the validity of research outcomes.
Alzheimer Europe has called for the direct involvement of persons living with dementia in research [48].In addition, Swarbrick et al. (this review) advise to involve persons regardless of their cognitive abilities [23].These statements question the involvement of proxies, such as carers, professional caregivers and others involved in the care of PLWD.While PLWD and persons with other cognitive problems constitute a significant group within residential and nursing homes [7], none of the studies included in this review have provided methods to directly involve persons with more advanced stages of dementia.This raises the question if research methods should be adapted to allow those with more advanced stages of dementia to be involved themselves or if, concerning the progressive nature of the disease, it is more appropriate to involve proxies.And secondly who should these proxies be?Those that care for and live with persons with an advanced stage of dementia, or for example a person living with an early stage of dementia to represent the voices of persons with more advanced stages of dementia [31]?
Future research should adopt our example for stricter requirements for involvement and transparency about the involvement methods used.This will reduce tokenistic involvement and further promote the culture shift towards meaningful involvement.In addition, future research should assess the impact of the involvement methods that are described in this review.One of the first instruments that that may be used to do so in varying healthcare settings is the Public and Patient Engagement Evaluation Tool (PPEET) [49].Moreover, scholars in this review stress, and we agree with this, that future research is needed on the involvement of persons with more advanced stages of dementia to ensure their voices are not excluded from research [33,34].

Conclusions
This review provides an overview of the existing methods used to actively involve PLWD, LTC users, and carers in scientific research.Our findings show that their involvement is feasible throughout all research phases.We have identified five different methods for involvement, four different roles, and two models for co-research.Our results suggest that planning enough time for involving PLWD, LTC users, and carers in research, is important to ensure that researchers have time to build a trusting relationship and meet their personal needs and preferences.In addition, researchers are advised not to presume the meaning of burden and to avoid a deficit perspective.A flexible or emergent design could aid involved persons' ownership in the research process.

Fig. 1
Fig. 1 Preferred Reporting items for Systematic Reviews and Meta-analyses (PRISMA) flow diagram

First Author, year, country of study Topic of study People involved (lived experienced experts) Setting of involvement Study subjects Theoretical underpinnings of involvement Methods used Quality score
General characteristics of included studies

Table 2
Overview of the involvement methods and their implementation of included studies